The collar is used to align the top clamp plate to the A plate of the mold. This is a common option for metric mold bases in Europe.
Resources

Looking for an answer? You can send a question to our support team or search our FAQs.
Need CAD data, a technical guide, or MSDS? Visit our Resources Center.
Want to purchase product? Shop the online catalog.
Interested in a career? View the list of available positions.
Need to contact us by phone?